What is this?!

[Ayato123]

I was in the middle of a Team dungeon with another player and sudenlly everything stoped and said that there is an error with main quest. I've done main quest 3 hours ago, and there was nothing blitzing either. I couldnt finish dungeon, couldnt exit or anything so I had to refresh everything. This is first time it happened so I had to report it.

[Zmaj81]

This happens when the first time you go to TD, and attack the opponent at the same time with another player. Then you receive this error. The only solution is to "refresh" the page.